1. Field of the Invention
The present invention relates to a color image forming method using a transfer belt and a bias apparatus in secondary transfer of an image forming apparatus, in electrophotography, electrostatic recording, electrostatic printing, and the like.
2. Description of the Related Art
In electrophotographic image forming apparatuses, when a toner image is transferred onto a recording medium directly or indirectly from an image carrier, on which the toner image has been formed, toner scattering (hereinafter, “dust”) can occur. Particularly, dust is likely to be generated in a gap on an immediately downstream side of a primary transfer nip.
This problem occurs due to discharge generated in the gap when the recording medium is moved from a nip to the gap. Conventionally, a unit that positively reduces the discharge has not been provided (see, for example, Japanese Patent Application Laid-open No. 2000-298408 and Japanese Patent Application Laid-open No. 2004-287383).
There has been a proposal in which a conductive brush applied with a bias of a reverse polarity to a charge of an intermediate transfer belt is brought into contact with a rear face of the intermediate belt at a position on the downstream side of the nip (see, for example, Japanese Patent Application Laid-open No. 2004-227016)). In this proposal, however, if there is nonuniformity in a neutralizing effect by the conductive brush member, discharge occurs on an entrance side of the nip in a transfer unit for the next color, and dust of the toner image is easily generated.